1. Field of the Invention
This invention relates to a method for manufacturing charcoal from paper sludge and an apparatus therefor.
2. Description of the Prior Art
Charcoal heretofore in use has been made from wood as the main raw materials thereof such as Quercus serrata, Quercus glandulifera and oak etc. However, these woods cannot be cut down without any restriction, and once cut down or lumbered, at least five years are required until they grow up again. In veiw of the limited area of mountains and forests in the world, there is a limit in the supply of raw materials.
As for a conventional method of manufacturing charcoal, the method of baking woods in a casserole had been employed. In Yamanashi Prefecture, Japan, charcoal making has been made by putting 2,000 kgs of wood material in an oven, in which case firewood of 200 kgs corresponding to 10% of the weight of the wood material was required. The firewood of 200 kgs is let to burn continuously for three days and then left as it is for about six or seven days until it goes out completely. Meanwhile, the degree of carbonization of the wood is discriminated by checking the colour of the smoke or by pressing a match stick to a stack to see whether or not it can be ignited in twelve or thirteen seconds. In the above-mentioned method of discriminaing the degree of carbonization, the heat loss rate of the firewood reaches about two thirds of the total heat quantity, that is; more than half of the firewood of 200 kgs is burnt ineffectively. Further, the partition wall on the side of a fuel hole must be broken to take out the inside charcoal thus produced.
Thus, generally speaking, in the conventional manufacturing process of charcoal, there is a limit in the suppply of wood materials. The thermal efficiency of charcoal making apparatus is low, and the accommodating capacity of the oven is reduced in the case of bent wood materials to be used thereby reducing the production efficiency and increasing the cost of the charcoal thus obtained.
On the other hand, the process of manufacturing solid fuels from paper pulp wastes is well known. For example, disclosed in the Japanese Patent Publication No. 21222/1972 is a method of manufacturing a solid fuel which comprises recovering paper pulp waste, charging the paper pulp waste into a mold, pressurizing the pulp waste at a pressure of 10 to 20 kg/cm.sup.2 so as to achieve dehydration, then drying the dehydrated pulp waste so as to obtain moldings or preforms having a moisture content of about 10%, dipping said moldings in a liquid fuel such as heavy oils etc. and finally coating the outer periphery of said moldings with molten paraffin. Further, in the Japanese Patent Publication No. 8962/1976, there is disclosed a method of manufacturing a solid fuel which differs from the aforementioned process in which kerosine or gas oil is used instead of heavy oils, and also polyethylene or polypropylene is used in place of the molten paraffin for coating the moldings.
However, in any of the above-mentioned methods, oils such as heavy oils and kerosine are used as fuel and dry distillation process is not employed in the manufacturing process.